Portable agitator



Jan. 2, 1934. N. K. DAVIS El'AL 1,942,277

PORTABLE AGITATOR Filed March 17, 1930 2 Sheets-Sheet l [FllllljlllllllllllIlllllllllll1H INVENTORS. A/O R191: A DA VI: A LFRED .EJVASOI ATTORNEYS. v

Jan. 2, 1934. N. K. DAVIS El AL PORTABLE AGITATOR Filed March 17, 1930 2 Sheets-Sheet 2 INVENTORS.

flora/s A4 0/! VA BY ALFRfD 2 M450 ATTORNEYS.

Patented Jan. 2, 1934 UNITED STATES PATENT OFFICE 1,942,277 PORTABLE AGITATOR said Davis Application March 17, 1930. Serial No. 436,408

3 Claims.

This invention relates to the transportation of ready mixed concrete from central mixing plants to the job or point of use of the mixed material and the objects of the invention are to provide a power-driven agitator which will maintain the pre-mixed concrete in the mixed conditon so that it will not separate out during the hauling to the job.

A feature of the invention is to provide the apparatus complete with power plant on a trailer so that a common motor truck may be used to haul one or several of the agitators to the job and thus obviate the expense of tying up a large motor truck for each agitator, though if desired, the agitator may be mounted directly on a motor truck.

Another feature of the invention in its most complete form is to provide a separate engine for driving the agitator so that a slow even motion can be secured independent of the varying speeds of the truck engine. Other features of the invention are the arrangement of filling and discharge gates, drum drive and brake, self-discharging baflles'within the drum, together with still other features which will appear in the following description and accompanying drawings.

In the drawings Fig. 1 is a plan view of the agitator complete on a trailer with its engine in place.

Fig. 2 is a side elevation of Fig. 1 and showing in dotted lines the tilted or discharging position of the agitator drum.

Fig. 3 is a rear elevation of the agitator.

Fig. 4 is an enlarged view of the rear gate and Fig. 5 is a cross section thereof as seen from the line 5-5 of Fig. 4.

Fig. 6 is a fragmentary enlarged longitudinal section showing the side or filling gate, and Fig. '7 is a cross section thereof as seen from the line 'l7 of Fig. 6.

Fig. 8 is a cross section of the agitator drum showing the self-discharging agitating blades in the drum, and the air inlet check valve at the forward end of the drum.

Fig. 9 is an enlarged longitudinal section of the air inlet valve. Fig. 10 is a detail of the tilting frame latch.

In further detail the apparatus comprises a road vehicle, here shown as a heavy rubber-tired trailer 1 with draw-bar 2 for connecting to a motor truck or to a similar trailer, while mounted upon the chassis frame 1' of the vehicle is a tiltable frame 3 pivoted at 4 to the vehicle frame and which tiltable frame is provided with means for lifting its forward end, here shown as a conventional form of hydraulic dump hoist 5 operated by a liquid in a pipe 6 from a pump 7 cperated by an engine 8, the power applying elements of the hoist and the engine being carried by the vehicle frame.

Mounted upon the tiltable frame is a horizontally disposed cylindrical drum 9 supported on rollers 10 carried by the tiltable frame, while surrounding opposite ends of the drum are holddown straps 11 secured at their lower ends to the tiltable frame. These straps each comprise spaced members supporting between them fixed blocks 12 preferably of wood normally out of contact with the drum but sufficiently close as to prevent material displacement of the drum from its supporting rollers 10 when going over a bump on the road, while between the forward pair of straps is a band brake l3 normally out of contact with the drum, pivoted at 14 to the straps and provided with an operating lever 15 locked by a link 16 I when the brake is set so as to hold the same against rotation.

Surrounding the forward end of the drum is a gear ring 17 in mesh with a small pinion 18 positioned under the gear ring on a countershaft 19 supported partly by the engine frame and at the other by a cross member 20 secured to the vehicle frame and on which the forward end of the tiltable frame rests, the arrangement being such that upon tilting the frame, the gear ring will lift out of engagement with the pinion.

The gas engine 8 here shown is of the self contained industrial type provided with right-angle reducing drive gears in box 21 at the forward end and oppositely extending power shaft 22 one end of which is geared as by the chain 23 to the countershaft 19, while the opposite end is arranged for driving the hydraulic hoist pump for tilting the drum, both drives under control of suitable clutches indicated at 55 and 56.

On top of the drum is a loading door or gate 24 seated over an opening in a depression 25 formed in the cylindrical wall of the drum and which door is loosely hinged at one edge to the drum as at 26, provided with a handle 27 at the opposite edge and held in closed position by a cross bar 28 slotted at both ends to receive wing bolts 29 pivoted at their lower ends at 30 to lugs 31 secured to the depressed part of the drum. A suitable gasket 32 is provided between the door and a lip 33 surrounding the drum opening.

At the rear of the drum and adjacent one side is a sliding discharge gate 34 mounted in ways 35 and actuated by short racks 36 engaged by pinions 37 carried on a shaft 38 in turn revolvably mounted on the ways 35. At the end of shaft 38 is an operating handle or handwheel 39 which may be removed and carried elsewhere on the truck when the drum is revolving. The gate may be drawn down tight when closed by means of an eye bolt 40, and will stay in opened position by friction of the parts.

In Fig. 5 the cross section of the gate, it .will be seen, that the lower edge of the gate is sealed by abutting against a rubber strip 41 carried on a lip 42 extending along the bottom edge of the door opening and secured to the drum, while a soft rubber hose 42' secured to the drum adjacent the upper edge of the gate opening insures the gate against leaking.

When dumping the drum is locked against rotation by the brake 13 with the rear gate in lowermost position, and when in such position the agitating blades within the drum all slant downwardly as shown in Fig. 8 and a certain air inlet valve 43 is positioned at the highest point above the load.

The agitating blades 44 at the top of the drum are straight radial fins secured to the inside ofthe drum and the two lower blades 45 are similar fins but are mounted on a plurality of brackets'46 spacing them a few inches from the drum wall and also holding them at opposite angles converging downwardly so that all the material above will slide off by gravity either over the blades or down behind them.

The air inlet valve 43 comprises a pipe nipple 4'7 screwed into the front head and fitted with a plug 48 slidably supporting a bolt 49 resiliently urged outward by a spring 50 and the inner end of the bolt carrying a soft rubber washer 51 seating across the opening to close the same, while slots 52 around the sides of the nipple 4'7 admit air'to the drum when the valve is drawn inwardly upon the rushing of the concrete from the rear gate when the same is opened and the drum elevated.

Without this valve inlet the discharge sputters and the heads of the drum vibrate excessively in trying to balance the varying pressure as the concrete gushes forth intermittently with the inrush of air through or over the issuing mass.

The forward end of tiltable frame 3 is held down by a latch 53 linked at 54 to the hoist clutch so as to automatically release the frame for tilting. (See Fig. 10).

In considering the invention as set forth it will be seen that it is quite different from a concrete mixer in which the materials are actually mixed from an unmixed condition in the device while being transported along the road, as such mixing requires a considerable horsepower withconsequent robbing of the truck engine so that the truck must frequently be run in second gear or the engine would stall, whereas in the present apparatus the materials are all premixed with the water at a large powerful central mixing plant so that an absolutely homogeneous mixture is assured before it is loaded into the agitator drum, then the drum is given a slow rotation just sufficient to keep the material mixed thus requiring but a very small amount of power which if taken from a truck engine would not impair the pulling power of the truck, or if taken from an auxiliary engine as contemplated will keep the drum revolving slowly at constant speed regardless of the speed of the truck engine which of course varies with every speed of the truck or drivers pressure on the throttle.

Another feature of great importance is that since the water is all premixed with the concrete materials no water is carried on the vehicle, and no water piping is required in the drum for ejection of water, so that in consequence the agitator drum may be substantially filled with the mixed concrete and with a given size drum nearly twice the quantity of concrete may be hauled thus further reducing the investment per unit of concrete supplied to a given job, and when hauling for large jobs or road work several trailer agitators may be hauled by a single motor truck.

The apparatus therefore distinguishes clearly from a concrete mixer and forms the basis of a MC new method of commercial purveying of concrete wherein the mass is properly mixed under proper conditions in a central plant and merely kept in agitation while in transportation by mechanism representing but a fraction of the investment per unit of concrete delivered.

We claim l. A horizontally disposed cylindrical agitator drum, means mounting said drum for revolution, a discharge door at one end of the drum, and a charging door on the side of the drum seated in a depression in the circular wall there of, said charging door hingedly connected to the drum, a bar extending across the door, and pivot bolts extending from the drum engaging opposite ends of the bar and means for locking the charging door in closed position.

2. A horizontally disposed cylindrical agitator drum, means mounting said drum for revolution, an eccentrically positioned discharge door at 120 one end of the drum, agitating fins supported in said drum arranged to all slant downwardly from their points of support for discharge of material by gravity when said discharge door is lowermost and including fins in the lower portion of the drum carried on brackets spacing them from the wall of the drum and converging downwardly.

3. A horizontally disposed cylindrical agitator drum, a supporting frame, means mounting the driun on said frame for revolution including rollers supporting the drum from below, arms partially encircling the drum secured at their ends to said frame, and a brake carried by said arms adapted to bear against the drum for lock- 5 ing the same at a desired point of revolution. 

